50.0 MB (3.0 MB compressed)
5181 x 3373 pixels
43.9 x 28.4 cm ⏐ 17.3 x 11.2 in (300dpi)
SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
Early battery operated hearing aid dating from around 1910. It was known as The Ardente and was manufactured by R.H. Dent of Oxford Street, London. This invention followed the new technology of the time; microphones and batteries. It is made of metal and worked by amplifying sounds.
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